Here is a simple version of the 'logo' scripting language that I remember
from the BBC (and those nifty little robotic turtles).

The only real difference here, is that I have added a 'turtle stack' which
is particularly useful in recursive systems. Calling 'Hatch Turtle' will
spawn a new turtle in the current position and take all control statements
until a 'Kill Turtle' command is received. At this point, control will
return to the turtle being used before the 'Hatch Turtle' call.
You must declare, in advance, the stack size, with -t n (where 0<n<65535).

options:
-h			--help		you're reading it
-c			--commands	list valid commands
-t			--turtles	maximum turtles to be hatched
-x			--xpos		starting x coordinate
-y			--ypos		starting y coordinate
-v			--tox		point towards x coordinate
-w			--toy		point towards y coordinate

For example,
HT
LT 45
FD 3
KT
RT 45
FD 3

will give:	not:  (turtle starts at the x, facing north)
                 
\         /          /
  \     /          /
    \x/          /
                x
                 \
                   \
                     \

See 'tree' for a totally cryptic, but very handy application of this.

Commands:

(Feel free to implement more commands)
FD x    	- Move ForwarD x points
BK x     	- Move BacKward x points
LT x     	- Left Turn x degrees
RT x     	- Right Turn x degrees
HT       	- Hatch Turtle
KT       	- Kill Turtle
PU       	- Pen Up off the pad
PD       	- Pen Down onto the pad
PC r,g,b 	- Pen Colour r,g,b (where 0 < [rgb] < 65536)
HOME	 	- Go back to start pos
REPEAT n [...]	- Repeat ... commands n times

KNOWN BUGS:
You can't nest repeat statements
Minus signs in repeat statements are ignored, just add 180 to your angle... :)

